I am looking to do my first partial mash and I have been seeing instructions for using a mash thickness anywhere from 1 to 1.5 quarts of water per pound (per 450g). What does the thickness of a mash change? Are there any calcuations that need to be adjusted based on this thickness?

Also, does changing the ratio of the sparge water to pounds of grain change anything?

I typically do a 5 gallon (19 litre) batch and a 3 gallon (11 litre) boil (do not have the equipment for a full boil yet). What is a typical ratio. I have read that a thicker mash will provide a fuller body and sweeter taste. However the tradeoff I've seen is that the sugars may not ferment fully, is that accurate?

What is recommended for a beginner partial masher?

Thanks, ~ Tom

  • This is a useful question (and answer) here. I am aiming to try to reproduce one recipe (in this case English bitter) several times and only change one variable to get a feel for things. Tomorrow I will be going for varying the mash thickness.
    – Poshpaws
    Jun 15, 2011 at 14:27

1 Answer 1


While many people cite the changes in body and fermentability that can come with changes in water to grist ratios, the impact from 1qt/lb (~ 2l/kg) changing to 1.5 qt/lb (3l/kg) is not noticeable at all, IMO. I have only noticed the impact when going from 1qt/lb to 3 or more qt/lb.

The main concern with calculations is that if you are batch sparging you can expect a larger run off volume with more water in the mash (obviously). That only comes into play as you are calculating (estimating) your sparge water for the second runnings. (I supposed this also plays into ohm much sparge water is need for a fly sparge set up too).

If you are just getting started with partial mashes, don't fret over this too much yet, its a small small trivial factor in the final beer. Stay focused on hitting proper mash temp constantly and getting good sparges. Stick with one water to grist ratio too, like 1.5qt/lb, for your next several batches. Its about consistency at this point in the learning curve. The fewer variables you mess with the better.

  • massive +1 for consistency - i'm learning the same thing myself and it's really good advice. Jun 16, 2011 at 13:37

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